Horizontal and vertical parity

The horizontal and vertical parity is used in some block codes for a combination of (LRC / VRC) checking to detect errors. The LRC: Longitudinal Redundancy Checking ("Horizontal Redundancy Checking") and the VRC: Vertical Redundancy Checking ("Vertical Redundancy Checking" 3. 4;).

Process

The process for calculating block parity is as follows:

• The characters to transmit are grouped into blocks of m rows and n columns
• The parity bit of each row is calculated and added at the beginning (or at the end, according to agreement) of the row
• The parity bit of each column is calculated and added to the beginning (or at the end, according to agreement) of the column

The final block to transmit will therefore have a row and a column more than the original.

• The new column will be formed by the horizontal parity bits of all rows
• The new row will be formed by the vertical parity bits of all columns.
• Additionally, a bit of cross parity is used which is calculated from the parity bits of rows and columns.

Horizontal and vertical parity checks are used to detect and correct possible errors that may occur during data transmission.

The following is an example in which the parity of a 48-bit block is checked, distributed in 6 rows of 8 bits each. Even parity is used.